The present invention relates generally to optics, and more particularly, to optical fiber-based remote gas leakage monitoring with sensor identifier.
Following the rapid growth of the internet traffic, optical fiber is exhaustively deployed especially in metropolitan area as the optical access network infrastructure. In the optical access network, multiple optical channels are launched using a wavelength division multiplexing (WDM) technique following established standards. Wavelength allocation in typical standards, gigabit Ethernet-passive optical network (GE-PON), ten Gigabit Ethernet (10 GbE) PON, and future time and wavelength division multiplexing (TWDM) PON are summarized with fiber loss in FIG. 2. As shown in FIG. 2, upstream (US) and downstream (DS) for 1G, 10G and multiple wavelength (X) channels in TWDM-PON are allocated from 1,280 nm to 1,625 nm. Wavelength region from 1,625 nm to 1,650 nm is reserved for future use. Therefore, a wavelength window longer than 1,650 nm is free in the current standards.
A challenge for fiber-based remote methane gas leakage monitoring in an optical network is how to identify a particular gas sensor. An optical distribution network in a PON setting has multiple optical fiber lines after a passive optical splitter and the probe signal is returned from multiple sensors. If distance from optical line terminal OLT to one optical network unit ONU is different from the distance from another OLT to another ONU, two probe signal pulses returned from the two different OLTs are distinguishable based on referring difference in the different round-trip times. However, it is hard to identify the two probe signals returned from the two different OLTs from the OLT to their respective ONUs are similar.
Prior activity of remote methane gas leakage monitoring is limited to use of one optical fiber line for one sensor thereby avoiding a sensor identification problem. Such one optical fiber line use for one sensor is severely limited and cannot be used in existing network infrastructures.
Accordingly, there is a need for identifying gas leakage sensors in an optical network that overcomes limitations of current capabilities.